class Container {
  static of (value) {
    return new Container(value)
  }
  constructor(value){
    this._value = value
  }
  map(fn){
    return Container.of(fn(this._value))
  }
}

class Maybe {
  static of(x) {
    return new Maybe(x)
  }
  isNothing() {
    return this._value === null || this._value === undefined
  }
  constructor(x) {
    this._value = x
  }
  map(fn) {
    return this.isNothing() ? this : Maybe.of(fn(this._value))
  }
}

module.exports = { Maybe, Container }